The present invention relates to the field of electrical transformers and inductors and particularly to a method and an apparatus for constructing continuously wound magnetic cores of transformers and inductors.
Transformers and inductors and the construction thereof is common in the art. FIG. 1 depicts an exemplary electrical transformer known in the art, shown generally at 10. The transformer 10 comprises a double coil transformer having a first coil bobbin 12 and a second coil bobbin 14. Each of the coil bobbins 12 and 14 typically has a turn wire (not shown) wrapped about the bobbin. The turn wire of the first coil bobbin is connected to the turn wire of the second coil bobbin by an electrical wire 16. The electrical wire 16 terminates in a prong 18 which provides a means for connecting the transformer 10 to another device. The first and second coil bobbins 12 and 14 include openings 20 and 22, respectively.
The electrical transformer 10 further comprises a wound core of magnetic material 24. The magnetic material 24 is wound about both the first coil bobbin 12 and the second coil bobbin 14 through the openings 20 and 22, respectfully, to form a magnetic transformer core 26. The magnetic material 24 is typically a magnetic strip wound to a predetermined thickness and cut to form a trailing edge 28. The trailing edge 28 is secured to the underlying magnetic material 24 by welding or other common adhesive process.
There are several common practices known in the art for assembling the magnetic material 24 within the transformer 10 to form the magnetic transformer core 26. In one method, the transformer core 26 is formed out of a stack of laminations which are constructed utilizing commonly known techniques such as interleave, butt-stack, etc. The second commonly implemented method for constructing the magnetic core 26 of an electrical transformer 10 involves assembling two pre-formed cut magnetic core halves about the wire coil. Although commonly implemented, these methods of manufacturing the magnetic core elements of electrical transformers are very time consuming and costly to the manufacturer.
Another known method for assembling magnetic transformer cores utilizes a core winding mechanism which winds a magnetic material in and through openings formed in a wire coil bobbin such that the leading edge of the magnetic material is continuously threaded through the opening(s) formed in the bobbin(s) to form a wound transformer core. In effect, this method pushes the magnetic material through the opening of a wire coil bobbin to form a magnetic core there about. The resulting magnetic core is fashioned into a predetermined shape such as a rectangle, etc.
This winding method, however, encounters difficulties when utilizing certain magnetic materials. Thin magnetic materials tend to buckle and jam the winding mechanism when forced in and about the coil bobbins thus inhibiting the winding process. Thick or hard magnetic materials form bulkier magnetic transformer cores. Higher stresses are placed upon the thick material thus resulting in the degradation of the magnetic properties of the material. Further, a winding mechanism as described above is insufficient in attaining a prescribed tension of the magnetic core material, especially when thick or hard magnetic material is used.
U.S. Pat. No. 4,592,133 to Grimes et al ('133), incorporated fully herein by reference, teaches a method of constructing an electrical transformer which entails winding an electrical wire about a pre-formed laminated magnetic core. Similarly, U.S. Pat. No. 5,860,207 ('207) to Knight et al, incorporated fully herein by reference, teaches a method of constructing an electrical transformer by preforming a laminated magnetic transformer core and winding a conducting coil about said core by use of a winding bobbin. However, neither the '133 nor the '207 patent teaches a winding technique for the construction of the transformer core, thus both referenced patents require implementation of costly and time consuming traditional core manufacturing methods as are discussed herein above.